Single sensor to display DHCP scope status

Hi Tom,

Awesome work, thanks for sharing! The script will find its way into our PRTG Sensor World soon :)

Kind regards,
Stephan Linke, Tech Support Team

I forgot to credit some sources that helped me to figure out this solution in addition to the PRTG KB articles and documentation.

https://lockstepgroup.com/blog/extreme-basics-of-prtg-custom-sensors-with-powershell/ https://thedomainiown.wordpress.com/prtg-related/general-custom-exe-script/

After 6 months: Has there been any progress implementing this as an "out-of-the-box"-sensor?

I'm afraid this is not planned as a native sensor. It's part of the script world now, and if there is enough usage there, we can consider building a native sensor.

That is sad to hear. It seems like Paessler is more and more ignoring new ideas and improvement recommendations from users. Don't get me wrong. Support has always been very good. Questions to support@ always get answered very fast. But in regards of improvements and enhancements to the system I feel pretty ignored right about now as I have brought in at least 10 new ideas for improvements over the last year and not even one of them was picked up. I always read "that is not planned". :-(

Please bear in mind, we've got 200,000 installations of our software, often with several users per installation working with our applications. It's in the nature of being a user of any product that you'll come up with ideas much faster than the ideas can put into reality. This applies to software as to pretty much any other product.
That means we have to focus on implementing those ideas where most users benefit from. Because even if we've had one developer per user, it would still be impossible to implement each idea, because thinking of an idea is instant, whereas putting it into code, testing it, documenting and supporting it, isn't instant.
So we have to say no a lot. That does not mean though, that we like to say no, it simply is the reality we live in. And it doesn't mean that the rejected ideas aren't useful in their specific use cases. It's always a compromise.

Hi Torsten,

I understand your point, but in this case sounds like an Excuse. There are many many people who would be very glad to have this sensor available. It is not a random request. The DHCP service is one of the most critical elements in the infrastructure. Having a ping is not enough.

I hope that this can be taken not as another stupid request, but as a very important one.

Regards.

Hi Tom,

Thanks for the great script. I made a few changes to allow for the fact that my DHCP server is running 2008 R2 and there for didn't have the required PowerShell command get-dhcpserverv4scopestatistics.

Since my PRTG server was running Server 2012 R2 I added the DHCP Server Tools feature to it and then used the belwo modifed version of your script. Basically I just removed the invoke piece and run the get-dhcpserverv4scopestatistics command directly from the PRTG server.

Add the following parameters separated by spaces to the PRTG parameters field in the same order as listed. Powershell requires them to be surrounded by single quotes.

Parameters Example

Script

Param(
[string]$scopeid,
[string]$hostname,
[string]$Username,
[string]$Password
)

# create credentials
$SecPassword = $Password | ConvertTo-SecureString -AsPlainText -force
$cred = new-object -typename System.Management.Automation.PSCredential ($Username, $SecPassword)

# Create session and run script. Use invoke-command with credentials. Import scopeid variable into scriptblock.

$ret = (get-dhcpserverv4scopestatistics -ComputerName DhcpServername -ScopeId $scopeid).PercentageInUse 

# output data for prtg to use
write-host $ret":DHCP Scope $scopeid Used: $ret%"

# Do some housekeeping
Remove-Variable -Name scopeid

# The exit command seems to help end the script to avoid timeouts.
exit

If you are running 2008r2, I believe you would need to install the Microsoft Framework 3 or higher.

Hi,

is the script still working on any system? We have a 2016 DHCP server, but get no information back from the script.

Dear PekkaHopp,

in order to debug it, please open the sensor's settings tab and enable the sensor option "Write Exe result to disk". After the next scan, the log files are in "C:\ProgramData\Paessler\PRTG Network Monitor\Logs (Sensors)" where you can analyze the script output.

My newest DHCP server is Windows 2012 Standard.
I'm using the script from Luciano (normal EXE, not Advanced EXE).

I've not been able to create a multi-scope sensor.

Dear Corné,

please also open the sensor's settings tab and enable the sensor option "Write Exe result to disk". You find the log in "C:\ProgramData\Paessler\PRTG Network Monitor\Logs (Sensors)" after the next sensor scan, allowing you a look at the output.

For example, it could be that the parameters were provided wrongly, or that the script has not enough rights to run. In order to address the latter issue, please check the script sensor's security context.

Dear PekkaHopp,

Be sure that you have created this in the 32-bit Powershell environment on your probe that will be running the script. For troubleshooting purposes, run the script from the Powershell window to see if it returns information or throws an error message.

I second the request of a native DHCP scope sensor as well, since this is really a critical service for us.

In the meanwhile I use a little modified version of the script I found on Reddit: https://www.reddit.com/r/prtg/comments/632z0d/script_monitor_dhcp_scope_usage/

Param (
    [STRING]$serverName
)

$dhcpScopeStats = Get-DhcpServerv4ScopeStatistics -ComputerName $serverName

$xmlOutput = '<?xml version="1.0" encoding="UTF-8" ?><prtg>'

foreach ($scope in $dhcpScopeStats)
{
    $xmlOutput = $xmlOutput + "<result>
        <channel>$($scope.ScopeId)</channel>
        <value>$([math]::Round($scope.PercentageInUse))</value>
        <unit>Percent</unit>
        <limitmode>1</limitmode>
        <LimitMaxError>95</LimitMaxError>
        <LimitMaxWarning>90</LimitMaxWarning>
        <LimitErrorMsg>DHCP Scope is over 95%</LimitErrorMsg>
        <LimitWarningMsg>DHCP Scope is over 90%</LimitWarningMsg>
    </result>"
}

$xmlOutput = $xmlOutput + "</prtg>"

$xmlOutput

Set it up as xmlexesensor and the parameter of it to '%host' (including the single quotes). Requires the DHCP-Tools on the probe server.

In this way I can check the older 2008 R2 DHCP servers as well and have all scopes in channels.

Hello,

Can someone help me please All i keep getting is a percentage symbol but no value next to it. The sensors green and i've set limits but it just stays at 0% even though we're using a lot of the scope. Help please?

Dear KarbonHomes,

in order to debug custom scripts, please go to its sensor "Settings" tab, and enable "Write exe result to disk". The logs are written to "C:\ProgramData\Paessler\PRTG Network Monitor\Logs (Sensors)", and show the output produced by the script. In many cases, the output shows an error message which prevents the further execution of the Powershell program.

Hi,

Here's an improved version of your script that can take multiple scopes in a single sensor & also you don't need to specify scopes manually:

<# Add the following parameters separated by spaces to the PRTG parameters field in the same order as listed.  Powershell requires them to be surrounded by single quotes.

Parameters Example: '%host' '%windowsuser' '%windowspassword'
#>

Param(
[string]$hostname,
[string]$Username,
[string]$Password
)

# create credentials
$SecPassword = $Password | ConvertTo-SecureString -AsPlainText -force
$cred = new-object -typename System.Management.Automation.PSCredential ($Username, $SecPassword)

# Create session and run script. Use invoke-command with credentials. 

invoke-command -ComputerName $hostname -Credential $cred -ScriptBlock { 

$dhcpscopes = Get-DhcpServerv4Scope | where state -EQ active #get all active scopes

Write-Host 	"<prtg>" #start creating the XML format

#this part creates as many entries as necessary depending on the number of Scopes

foreach ($scope in $dhcpscopes) {


$scopeid = $scope.ScopeId.IPAddressToString 
$percentage = (get-dhcpserverv4scopestatistics -ScopeId $scopeid).PercentageInUse



Write-Host 	"<result>" 
		"<channel>$scopeid</channel>"
		"<value>$percentage</value>"
		"<LimitMaxError>90</LimitMaxError>"
		"<LimitMode>1</LimitMode>"
        "<float>1</float>"
		"</result>"

}

Write-Host 	"</prtg>"}


# The exit command seems to help end the script to avoid timeouts.
exit

Dear mbaybarsk,

thank you for sharing the script!

Please allow me these two remarks:

1) The script could produce more than 50 channels. PRTG officially supports only up to 50 channels. For stability, it would be useful to limit the foreach loop to a certain number of channels.

2) It could happen that the primary channels gets no data, for those purposes I recommend to create a channel with a static output which serves as primary one.

First I'd like to say thank you all for sharing your scripts and work.

This is what I'm using in our environment.

PRTG Server: Windows Server 2019

DHCP Server: Windows Server 2012R2

This script utilizes invoke-command.

<#
Sensor name: dhcpserverv4scopestatistics

exe/script: getdhcpserverv4scopestatistics.ps1

Parameters: '%host' '%windowsdomain' '%windowsuser' "%windowspassword"

sec context: use windows credentials of parent device

#>

Param(
[string]$ComputerName,
[string]$windowsdomain,
[string]$Username,
[string]$Password
)

$Username = "$Username@$windowsdomain"

# create credentials
$SecPassword = $Password | ConvertTo-SecureString -AsPlainText -force
$Credential = new-object -typename System.Management.Automation.PSCredential ($Username, $SecPassword)

$ret = invoke-command -ComputerName $ComputerName -Credential $Credential -ScriptBlock { Param($ComputerName) get-dhcpserverv4scopestatistics -ComputerName $ComputerName } -ArgumentList $ComputerName


# use system collections arraylist for performance
# alternatively maybe look into StringBuilder
# also adding / appending is more efficient vs += using @() array
$ArrayList = [System.Collections.ArrayList]@()


# prtg xml headers
$null = $ArrayList.add(
@"
 <?xml version="1.0" encoding="Windows-1252" ?>

 <prtg>
"@
)

# for stability reasons we may want first 50 highly used ScopeIds:
$ret =  $ret | sort -Descending PercentageInUse | select -First 50
<#
ScopeId          Free            InUse           PercentageInUse  Reserved        Pending         SuperscopeName
-------          ----            -----           ---------------  --------        -------         --------------
172.16.28.0      118             243             67.31302         25              0
172.16.6.0       87              117             57.35294         1               0
172.16.8.0       87              114             56.71642         9               0
#>
# prtx xml results
foreach($r in $ret) {
$ScopeID = $r.ScopeID
$PercentageInUse = $r.PercentageInUse
$null = $ArrayList.add(
@"
    <result>
        <channel>DHCP Scope - $ScopeID</channel>
        <unit>Percent</unit>
        <mode>Absolute</mode>
        <showChart>1</showChart>
        <showTable>1</showTable>
        <warning>0</warning>
        <float>1</float>
        <value>$PercentageInUse</value>
        <LimitMaxError>37</LimitMaxError>
        <LimitMaxWarning></LimitMaxWarning>
        <LimitWarningMsg>My custom note for warnings</LimitWarningMsg>
        <LimitErrorMsg>My custom note for errors</LimitErrorMsg>
        <LimitMode>1</LimitMode>
    </result>
"@
)
}

# prtg xml footer
$null = $ArrayList.add(
@"	
 </prtg>	
"@
)

# output data for prtg to use
$ArrayList

# The exit command helps to end the script and avoid timeouts.
exit

Hi, Can someone share the permissions required for this script to work without admin rights? I have added the user to the dchp-users and remote management groups yet I always get the error + CategoryInfo : PermissionDenied: (PS_DhcpServerv4ScopeStatistics:root/Microsoft/...ScopeStatistics) [Get-DhcpServerv4ScopeStatistics], CimException

Thanks

Permissions needed: Make sure the account used for running the script has permissions for remote script execution.

Dear Corné,

please check the security context you set for this sensor, as the probe service (using the local SYSTEM account by default) might not be allowed to run remote scripts. Instead, use the device's credentials.

Please also make sure that the powershell execution policy is configured to allow running the script (see Powershell command set-executionpolicy).

Not sure if anyone would find this useful, I took one of the above scripts and edited it to also show scope names with subnets. It should be noted to use this sensor in this post you have to set the Security Context to "Use Windows credentials of parent device". If it is left at the default the sensor will error out with no data found.

Param (
    [STRING]$serverName
)

$dhcpScopeStats = Get-DhcpServerv4Scope -ComputerName $serverName

$xmlOutput = '<?xml version="1.0" encoding="UTF-8" ?><prtg>'

foreach ($scope in $dhcpScopeStats)
{
     $ScopeName = $scope.Name
     $ScopeId = $scope.ScopeId
     $ScopeStats = Get-DhcpServerv4ScopeStatistics -ScopeId $ScopeId -ComputerName $serverName | select PercentageInUse
	 
    $xmlOutput = $xmlOutput + "<result>
        <channel>$($ScopeName) ($ScopeID)</channel>
        <value>$([math]::Round($ScopeStats.PercentageInUse))</value>
        <unit>Percent</unit>
        <limitmode>1</limitmode>
        <LimitMaxError>95</LimitMaxError>
        <LimitMaxWarning>90</LimitMaxWarning>
        <LimitErrorMsg>DHCP Scope is over 95%</LimitErrorMsg>
        <LimitWarningMsg>DHCP Scope is over 90%</LimitWarningMsg>
    </result>"
}

$xmlOutput = $xmlOutput + "</prtg>"

$xmlOutput

Hi All,

I'm getting this error when attempting to use this ps script, any help in getting this working?

I have the Syntax below

Param(
[string]$'Mgmt-Svr',
[string]$'Int.Net',
[string]$'username',
[string]$'password'
)

$Username = "$Username@$windowsdomain"

At line:13 char:9

+ [string]$'Mgmt-Svr',
+         ~

Parameter declarations are a comma-separated list of variable names with optional initializer expressions.
At line:13 char:9

+ [string]$'Mgmt-Svr',
+         ~
Missing ')' in function parameter list.
    + CategoryInfo          : ParserError: (:) [], ParentContainsErrorRecordException
    + FullyQualifiedErrorId : InvalidFunctionParameter

Hello parky,

using a hyphen in Powershell variables is problematic unless first created with New-Variable. For this parameter block the easiest way is to not use hyphens.

We're using this script for a couple of years now, without any problems. Since the last Windows Updates two weeks ago, we notice high CPU usage on the DHCP servers. The process wsmprowhost.exe is using 50% CPU. In Event Viewer it looks like this process is executing 58 commands for one scope. As we are monitoring five scopes and check every minute, there is almost non-stop high CPU usage.

Our environment: DCHP servers are Windows Server 2019. Installed updates two weeks ago: KB5017270, KB5018419 and Servicing Stack 10.0.17763.3460

PRTG Probe is Windows Server 2012. Installed updates two weeks ago: KB5018413, KB5018478, KB5018518 and KB5018457

Is anyone seeing the same issue and maybe has a solution?